Method for producing carbon black

ABSTRACT

A method and apparatus are provided for producing carbon black wherein in a carbon black reactor a first quench of effluent flowing through a quench zone is effected by contact of the effluent with water. The first quench cools the effluent to a temperature sufficiently low to stop pyrolysis. Downstream of the first quench is a secondary quench in which cooled smoke ahead of the filters is contacted with the effluent for secondary cooling the effluent. After the second cooling the effluent flows to an indirect heat exchanger wherein the effluent is again cooled, by indirect contact with a coolant in the heat exchanger, to a temperature sufficiently low to prevent damage to the filter system.

In the production of carbon black it is necessary to stop the pyrolysisat a certain point so as to produce a certain type of carbon black. Thisrequires cooling of the effluent flowing from the reaction zone to atemperature sufficiently low to stop the pyrolysis after a certainamount or degree of pyrolysis has been achieved. The degree of pyrolysisdetermines the type of carbon black produced. In the past it has beencommon to inject a coolant into the reactor for direct contact with theeffluent to cool same to the pyrolysis stopping temperature. Thistypically was accomplished by the injection of water into the quenchzone which has been effective to cool the effluent. Also, cooling hasbeen accomplished by injecting cooled smoke, which is recycled from theeffluent stream upstream of the filter system, into the quench zone toeffect cooling of the effluent. Both types have advantages anddisadvantages relative to one another wherein for example cooling withwater requires a small amount of water compared to the amount of smokenecessary to effect the quenching but then the injection of water hasthe disadvantage of producing a large amount of water vapor which mustbe handled by the filter system which relative to a smoke quenchrequires a larger filter system which is one of the major expenses in acarbon black producing apparatus. Also, with more water there is ahigher probability of water vapor condensation with resulting corrosionof the filter system. The use of smoke has the advantage of notproducing a large amount of gas thereby permitting a smaller filtersystem but then it has the disadvantage of requiring large amounts ofsmoke to effect the cooling. Smoke or gas quenching poses severalpractical problems in the introduction of such a large amount of smokeor gas into the reactor which physically requires a large inlet comparedto a water inlet and also requires a blower or compressor to pressurizethe smoke so that same can be introduced into the reactor. It is alsoknown in the art that a dual quench can be used wherein smoke is firstintroduced into the reactor to effect prequenching of the reaction whichis then followed by a downstream water or trim quench to effect finalcooling of the effluent. Such a process is disclosed in U.S. Pat. No.3,369,870, issued Feb. 21, 1968 to S. F. Ganz et al. However, in thispatent the water introduction into the effluent stream is accomplisheddownstream of an indirect heat exchanger which is positioned downstreamof the smoke introduction.

The present invention provides an alternate to the above describedprocesses and takes advantage of the relative merits of both theintroduction of water and smoke as quench fluids. From the filter systemstandpoint, the use of only water as the quench fluid requires thelargest filter system whereas the use of only cooled smoke as the quenchfluid requires the smallest filter system and the use of smoke and watertogether as quench fluids with the smoke being introduced upstream ofthe water quench requires a filter system between the twoabove-described processes. The present invention by introducing waterfirst and smoke second as the quench fluids provides a method wherein afilter system can be sized between the filter system required for smokefirst and water second and the size of a filter system required for atotal smoke quench, while still effecting adequate quenching of theeffluent. Also, by using water as the pre-quench fluid wherein smallerinlets can be used compared to smoke inlets, and since normally aplurality of pre-quench inlets are provided same can be closer together.

The principal objects and advantages of the present invention are: toprovide a method and apparatus for producing carbon black which iseffective for quenching the reaction and stopping the pyrolysis at apredetermined point; to provide such a method and apparatus whichrequires a minimum of change in existing equipment to accomplish thedesired end result; to provide such a method which will result ineffective quenching while minimizing the amount of gas which is requiredto be handled by a filter system thereby resulting in the need for asmaller filter system and reduced capital outlay for a carbon blackproducing apparatus; and to provide such a method and apparatus which iswell adapted for its intended use.

Other objects and advantages of the present invention will becomeapparent from the following detailed description taken in connectionwith the accompanying drawings wherein are set forth by way ofillustration and example certain embodiments of this invention.

FIG. 1 is a schematic illustration of a carbon black producingapparatus.

Referring more in detail to the drawing:

As required, detailed embodiments of the present invention are disclosedherein, however, it is to be understood that the disclosed embodimentsare merely exemplary of the invention which may be embodied in variousforms. Therefore, specific structural and functional details disclosedherein are not to be interpreted as limiting but merely as a basis forthe claims and as a representative basis for teaching one skilled in theart to variously employ the present invention in virtually anyappropriate structure.

The reference numeral 1 designates generally a carbon black producingapparatus which includes a reactor 2 which can be of any suitableconstruction such as those already known in the art and the illustratedreactor 2 is similar to that disclosed in U.S. Pat. No. 2,564,700. Thereactor 2 includes a precombustion zone 3 which has communicatingtherewith and downstream thereof a reaction zone 4 which has downstreamthereof a quench zone 5. Means 6 communicate with the precombustion zone3 for the introduction of combustion gases such as air and a combustiblefuel or a burning mixture of same, or hot gases of combustion, and asshown the means 6 includes a conduit which opens into the precombustionzone and is directed in a generally tangential manner to effect swirl orvortex flow of fluid therein. A make hydrocarbon introduction means alsoopens into either the precombustion zone 3 or reaction zone 4 and isoperable for injecting a make-hydrocarbon (sometimes called "oil" or"make oil") thereinto. This generally is a conduit 7 which has a spraynozzle on the end thereof as is known in the art. A venturi 8 can alsobe provided in the reaction zone 4 as is known in the art. Although avortex type reactor is disclosed above, it is to be understood that anysuitable type of carbon black producing apparatus can be used. Thequench zone 5 has an outlet 9 at the downstream end thereof and theoutlet 9 is connected to an indirect heat exchanger 11 via a conduit 12wherein effluent flowing through the quench zone and out the outlet 9 isconducted to the heat exchanger 11. The heat exchanger 11 can be of anysuitable type.

Filter means 14 of any suitable type such as a bag filter is in flowcommunication with the conduit 12 and the outlet 9 via a conduit 15which connects the filter means 14 to the heat exchanger 11. In thefilter means 14 effluent is separated into a gaseous phase or off-gasand a solid phase wherein the gaseous phase is taken as an overheadproduct out a discharge 16 and the particulate or solid portion of theeffluent is taken as a bottoms product out a discharge 17 which can thenbe conducted to other processing equipment such as pelleters and dryers,as are known in the art.

Quench fluid inlet means communicate with the quench zone 5 and as shownan inlet 19 is connected to a source 20 of liquid coolant such as water.Downstream of the inlet 19 there is a second quench fluid inlet 21 whichis connected to a source of cooling gas which preferably includes theconduit 15 upstream of filter 14 and downstream of the heat exchanger 11via a conduit 22. A suitable blower or other flow inducing device 23 isconnected in the conduit 22 so as to pressurize the fluid flowingtherethrough so that same can be introduced into the quench zone 5through the inlet 21. The inlet 21 is positioned between the outlet 9(also the heat exchanger 11) and the inlet 19 wherein the first quench(prequench) of the reaction is accomplished by water injected throughthe inlet 19 and the second cooling is accomplished by the injection ofcooling fluid injected through the inlet 21 and a third cooling isaccomplished by indirect heat exchange in the heat exchanger 11.

The present invention is more fully understood by a description of theoperation thereof. A burning mixture of combustible gas and air contactsa make-hydrocarbon injected through the conduit 7 and at a predeterminedpoint along the length of the reactor 2 the effluent containing smokewhich contains gases and carbon black in particulate form is contactedwith water injected through the inlet 19. It is to be understood thatthe reactor 2 can be provided with a plurality of inlets 19 positionedalong the length thereof with the choice of the particular inlet beingdictated by the particular carbon black desired to be made wherein thedegree of pyrolysis is determined by the length of time which, in turn,is determined by how far the effluent which is being pyrolyzed, flowsdown the length of the reactor 2 before quenching. A sufficient quantityof water is injected through the inlet 19 to lower the temperature ofthe effluent to a temperature sufficiently low to stop the pyrolysis ofthe make hydrocarbon wherein typically this temperature would be atemperature of up to about 2200° F. After the first cooling, the cooledeffluent flows further along the quench zone 5 and is then contactedwith cooled gas which preferably is smoke from the conduit 15 whichnormally contains some water vapor, from the introduction of water intothe quench zone, to further cool the effluent which also contains watervapor by virtue of the water introduced through the inlet 19. Theeffluent is cooled secondly at the inlet 21 to a temperature of up toabout 1800° F. and preferably between 1000° F. and 1800° F. After thesecondary cooling, the smoke effluent which now contains gases and watervapor as well as particulate carbon black and the other variouscomponent parts of the effluent are then passed through the heatexchanger 11 for a further reduction in the temperature thereof whereinthe temperature is lowered to a temperature sufficiently low to preventdamage to the filter unit but yet sufficiently high to preventcondensation of deleterious materials therein such as to prevent theformation of acids like sulfuric acid which also damages the filtersystem. This temperature is up to about 600° F. and is preferablybetween about 400° F. and 600° F. and most preferably about 450° F. Thecooled effluent after passing through the heat exchanger 11 is thenconducted to the filter means 14 for separation of the effluent into agaseous phase and a solid phase with the gaseous phase being dischargedthrough the outlet 16 and the particulate solid phase being dischargedthrough the discharge 17. A portion of the smoke and water vapor takenupstream of filter 14 is preferably recycled to be used as the coolingsmoke for injecting through the inlet 21. The remaining portion of thecooled smoke and water vapor is passed to filter 14 and the off-gas isremoved at 16 as a product which can be used as a heating material orthe like.

To further illustrate the present invention, the following calculatedexample is provided:

    __________________________________________________________________________                   1      2                                                                      All Water                                                                            All Smoke                                                                             3            4                                                 QI-2200° F.                                                                   QI to 2200° F.                                                                 Smoke Prequench-2200° F.                                                            Water Preq.-2200° F.                       QII-1300° F.                                                                  QII to 1300° F.                                                                H.sub.2 O Final Q-1300° F.                                                          Smoke to 1300° F.           __________________________________________________________________________    Recycle Blower Smoke                                                                            0   282,353  34,286      223,455                            at 20 psia, SCF/H                                                             Total to Filter, SCF/H                                                                       255,380                                                                              200,000 249,600      211,041                            Amount Cooled from                                                                           255,380                                                                              482,353 283,886      434,496                            1300 to 450° F., SCF/H                                                 Water Added     55,380.sup.(1)                                                                         0     49,600.sup.(2)                                                                             11,041                            (Shown SCF/H Steam Made)                                                      Vol. % H.sub.2 O (as steam)                                                                   (28)     0     (25)         (5.5)                             Added to Smoke, of Smoke                                                      __________________________________________________________________________     .sup.(1) Total liquid water added, 315 gph                                    .sup.(2) Total liquid water added, 239 g/n.                                  Reactor:                                                                             Precombustion Zone:                                                           Diameter, inches,    39         (99.06 cm)                                    Length, inches       12         (30.48 cm)                                    Reaction Zone:                                                                Diameter, inches,    15         (38.10 cm)                                    Length to Prequench,                                                          inches               48.sup.(1) (121.92 cm)                            __________________________________________________________________________     .sup.(1) Three prequench loci are installed on the reactor at 36 inches       (91.44 cm), 42 inches (106.68 cm), and 48 inches (121.92 cm) downstream       from the outlet of the precombustion zone. Only one prequench is used at      time, depending on the type of carbon black desired to be produced.      

    Length to final quench,                                                              inches               120        (304.8 cm)                             Operation: (for N330 Carbon Black):                                                  Tangential Air, SCF/hr.,                                                                           183,500    (5200 m.sup.3)                                Tangential Methane Fuel,                                                      SCF/hr.,             12,500     (354.2 m.sup.3)                               Axial Air, SCF/hr.,  4,000      (113.3 m.sup.3)                               Total Air/Fuel Vol. Ratio                                                     (150% of Stoichiometric Air)                                                                       15:1                                                     Make-Oil (120 BMCI, 700° F.                                            (371° C.) Mid-Boiling                                                  Point, Aromatic Oil),                                                         U.S. gallons/hr,     250        (946.25 liters/hr)                            Total Air/Oil, SCF/gal,                                                                            750        (5.62 m.sup.3 /liter)                         Prequench Water, at 48 inches,                                                g/hr,                63.sup.(2) (238.46 liters/hr)                            Cooled Smoke, at 120 inches,                                                  SCF/hr,              223,455.sup.(3)                                                                          (6331.96 m.sup.3 /hr)                  __________________________________________________________________________     .sup.(2) Prequench water added at 100° F. (38° C.)              .sup.(3) Smoke added at 450° F. (232° C.), 20 psia (135 kPa

    Carbon Black Properties (N330):                                                      .sup.(4) N.sub.2 SA, m.sup.2 /gm,                                                                  83                                                       .sup.(5) 24M4 DBP, cc/100 gm,                                                                      90                                                       .sup.(6) Photelometer,                                                                             85                                                __________________________________________________________________________     .sup.(4) ASTMD-3037-71T, Method A;                                            .sup.(5) U.S. Pat. No. 3,548,454, as measured after crushing, by Method B     ASTMD-2414-70;                                                                .sup.(6) ASTMD-1618-58T                                                  

From the above data it can be seen that in column 4 that although notthe least amount of total gaseous product flowing to the filter isprovided by the above invention, it is the next least compared to an allsmoke process with the data pertaining thereto listed in column 2.However, the use of the present invention does provide for less smoke tobe injected as a coolant and also does not have the physical limitationsof the size of the inlets as discussed above and also, the use of thepresent invention takes advantage of the quick quench provided by theinjection of water while minimizing the use of water to effect the endresult while maintaining a reduced amount of water vapor introduced intothe filter system over an all water quench method as shown in column 1.

It is to be understood that while there has been illustrated anddescribed certain forms of this invention, it is not to be limited tothe specific form or arrangement of parts herein described and shownexcept to the extent that such limitations are found in the claims.

What is claimed and desired to be secured by Letters Patent is:
 1. Amethod of producing carbon black comprising the steps of:(a) pyrolyzinga make hydrocarbon by heating said make hydrocarbon in a reaction zonewith hot combustion gases and thereby producing smoke, containing gasesand particulate carbon black; (b) flowing the smoke into a quench zone;(c) contacting the smoke in the quench zone first with water to therebycool the smoke to a temperature sufficiently low to substantially stopthe pyrolysis, thereby forming an admixture of smoke and water vapor;(d) contacting said admixture in the quench zone secondly with a coolinggas to thereby further cool the smoke to form a gaseous mixturecontaining particulate carbon black; and (e) separating particulatecarbon black from at least a portion of said gaseous mixture.
 2. Amethod as set forth in claim 1 wherein:returning to said quench zone afirst portion of said gaseous mixture as at least a portion of saidcooling gas.
 3. A method as set forth in claim 2 wherein:the cooling ofthe smoke with water produces said admixture at a temperature of up toabout 2200° F.
 4. A method as set forth in claim 3 wherein:the coolingof said admixture with the cooling gas produces said gaseous mixture ata temperature of up to about 1800° F.
 5. A method as set forth in claim4 including:thirdly cooling the smoke by passing said gaseous mixture inindirect heat exchange relationship with a coolant in an indirect heatexchange means after the second cooling and before the separating of thegaseous mixture.
 6. A method as set forth in claim 5 wherein:saidgaseous mixture is cooled to a temperature in the range of about 400° F.to about 600° F.